|Boston Red Sox – No. 59|
April 10, 1985 |
|Bats: Right||Throws: Right|
|June 29, 2009 for the St. Louis Cardinals|
(through May 27, 2013)
|Earned run average||4.66|
St. Louis Cardinals
After graduating from Madison High School, Mortensen went to Treasure Valley Community College, then Gonzaga University. Mortensen was drafted by the St. Louis Cardinals 36th overall in the 2007 Major League Baseball Draft.
On July 24, 2009, Mortensen was traded to the Oakland Athletics along with Brett Wallace and Shane Peterson for Matt Holliday. He was called up to the Athletics to replace Russ Springer on August 8.
Boston Red Sox
On January 21, 2012 Mortensen was traded to the Boston Red Sox for Marco Scutaro. Mortensen made his Red Sox debut on May 2, 2012 throwing three innings and giving up just one hit. On July 7, Mortensen was called up to the majors to be the 26th man for the Red Sox and Yankees double-header. Mortenson was recalled on August 8, when Vincente Padilla was placed on the disabled list. 
Mortensen throws four pitches: a four-seam fastball and two-seam fastball at 88–90 mph, a slider at 85–87, and a circle changeup at 79–81. The slider tends to be used more against right-handed batters, and the changeup is used more against left-handed hitters. Mortensen's slider has a somewhat unusual and unpredictable movement:
My slider isn’t a typical slider. It doesn’t necessarily break right-to-left. It has more depth to it, so it’s more of a down-ball. It also has three different movements, depending on where my release point is. When I really accentuate staying on top of it — away to a righty — it will have a little depth and a little right-to-left movement. If I try to throw it down the middle, it’s more straight down. Sometimes it kind of screws. It's basically because of the way I grip it. I kind of cock my wrist a little bit. To be honest, I try to throw it as hard as I can and it just kind of does what it wants to do.
On the night of October 2, 2009, Mortensen was arrested on suspicion of drunken driving and spent the night in the Santa Clara County jail.
- "Gonzaga University Baseball Players Who Made It to the Major Leagues". Baseball-Almanac.com. Archived from the original on 2012-08-10. Retrieved 10 August 2012.
- 2007 MLB.com Draft tracker
- "Cards offer 20 non-roster invites: Rasmus and Wallace among those to attend big-league camp". MLB.com. January 23, 2009. Retrieved January 26, 2009.
- Cards' Greene back on disabled list (June 29, 2009)
- Slusser, Susan (August 8, 2009). "Springer claimed by Tampa Bay - updated". The San Francisco Chronicle.
- "Brooks Baseball · Home of the PitchFX Tool - Player Card: Clayton Mortensen". Brooks Baseball. Retrieved 26 June 2012.
- Laurila, David (May 7, 2012). "Clayton Mortensen: Four Pitches, Hot Hand". Fangraphs. Retrieved 26 June 2012. Text " FanGraphs Baseball" ignored (help)
- Slusser, Susan (October 4, 2009). "Mortensen arrested for suspected drunk driving - updated". The San Francisco Chronicle.
- Career statistics and player information from MLB, or ESPN, or Baseball-Reference, or Fangraphs, or The Baseball Cube, or Baseball-Reference (Minors)